The invention relates to a guide rail for guiding and or tightening drive chains. Especially preferred embodiments of the invention relate to guide rails for chains of a control shaft drive of a vehicle internal combustion engine.
In French Pat. No. (FR-PS) 1 408 575, a chain guide rail is described formed of plastic and has a T-shaped cross-section.
German-Published Unexamined patent application No. (DE-OS) 30 49 106 shows a tightening rail for chain drives comprising a carrier made of sheet metal and a slideway lining body that consists of plastic and surrounds this carrier. The carrier and the slideway lining body are components that are produced independently of one another and interact via locking devices.
Finally, German Pat. No. (DE-PS) 34 17 100 shows a guide rail having a hollow duct housing that surrounds a chain on all sides. This guide rail is formed of plastic.
It is an object of the invention to provide a guide rail for the guiding and/or tightening of chains that, although it is relatively light, can withstand high strains and can be manufactured in a cost-effective manner.
According to the invention, this objective is achieved by providing that the guide rail is made up of a carrier made of a first plastic material and a slideway lining body made of a second different plastic material in a successive manufacturing opertion with said carrier and slideway lining body interengageably connected to one another along their length. Especially preferred embodiments form the carrier and slideway lining body by successive extrusion molding steps and interconnect the same by dovetailed connections. Certain preferred embodiments include reinforcing webs for the carrier and a double -T- flange carrier construction which minimizes weight while optimizing strength of the carrier. In certain especially preferred embodiments, the carrier is provided with bearing lugs for accommodating bearing pin connections at an internal combustion engine. The material of the slideway lining body is selected to optimize sliding bearing characteristics vis-a-vis the chain guided directly thereon and the material of the carrier is selected to optimize the carrying support functions while minimizing weight.
Principle advantages achieved by means of the invention are that the guide rail is of a light weight and nevertheless durably withstands the strains caused by the chain. In addition, the manufacturing method of the guide rail is economical because of the progressive manufacturing sequence-machining processes are essentially unnecessary. The construction also meets above-average requirements with respect to quality.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.